Over the last decade, people have begun to realize the need for and benefits of physical activity. As such, aerobic exercise (i.e. physical activities which strengthen the-heart muscle) such as running, rope jumping and aerobic dance have become popular. As a result of this renewed interest in exercise, increased attention has been given to the development of athletic footwear. For example, it has recently become an objective of footwear manufacturers to develop a shoe which is lightweight yet supportive and comfortable.
Typically, an athletic shoe includes an upper, an insole, a midsole and an outsole. The upper covers and protects the instep, heel, and side portions of the foot and is commonly constructed of leather, canvas or synthetic material (e.g., nylon) or a combination thereof. The upper is secured to the foot of the wearer by a lacing means, a buckle system or a VELCRO.RTM. closure system which overlies the wearer's foot in the instep area.
The particular sport for which the athletic shoe is chosen often dictates the material used to construct the upper. For example, the upper of a basketball shoe is constructed almost entirely of a heavy material such as leather because leather provides more support to the wearer's foot and ankle than canvas or nylon. A running shoe upper, however, is formed almost entirely of a synthetic material because such a material is lightweight, breathable and easy to clean. Depending on the material used to construct the upper, the typical shoe upper accounts for approximately 38-50% of total shoe weight.
The insole or insole board, which lies next to the foot under a sockliner, is the foundation of a shoe. It is that part of the shoe to which the upper is lasted and the sole attached. The insole may be made in one or two pieces and, for athletic shoes, is typically formed from particle board, cellulose board or other absorbent, lightweight material. To increase the flexibility of the insole board, some manufacturers provide transverse slits in the insole adjacent the metatarsal area. For a more flexible shoe, the upper may be sliplasted (as opposed to board lasted) by stitching a slip sock to the lasting margin of the upper. To complete formation of the shoe, the sliplasted upper is stitched or cemented to the shoe sole unit.
The midsole lies between the insole and outsole and is provided mainly to cushion the heel and forefoot of the wearer. Materials such as polyurethane (PU), ethyl vinyl acetate (EVA), polyester ethyl vinyl acetate (PEEVA), ELVALOY.TM. and more recently HYTREL foam are used to form the midsole. (HYTREL is a semi-crystalline, fully polyermized, high molecular weight, chemically stable, polyester elastomer composed of alternate amorphous and crystalline chains made by E. I. DuPont de Nemours and Co.) The midsole may be formed in one or more pieces and often includes a wedge or cushioning insert disposed beneath the heel of the wearer to effectively increase the amount of cushioning. During assembly, the midsole is typically bonded, either by cement or by fusion, to the insole of the shoe.
Finally, the outsole is that part of the shoe which comes into direct contact with the ground. The outsole is commonly molded from an abrasive resistant material such as rubber and is bonded or adhered to the bottom surface of the midsole to complete the shoe sole unit. The standard sole unit, consisting of the insole, midsole and Outsole, accounts for approximately 50-62% of total shoe weight.
In an effort to reduce the weight of athletic shoes, footwear manufacturers have, for the most part, focused their attention on decreasing the overall weight of the sole. One technique which has been employed to reduce shoe sole weight involves removing portions of the outsole which are not in direct contact with the ground or are otherwise not needed. U.S. Pat. No. Re. 33,066 to Stubblefield, for example, discloses a shoe sole where outsole material has been removed from beneath the metatarsal and rear heel portions of the foot.
More recently, shoe manufacturers have attempted to reduce the weight of shoes by forming the midsole from lower density synthetic foam materials. Although these foams are lighter in weight, they tend to break down more rapidly and sacrifice the amount of cushioning and support provided to the foot of the wearer.
Still another technique for reducing the weight of the sole involves removing an entire portion of midsole not specifically needed to cushion a particular area of the foot (e.g. the area beneath arch of the foot).
While some techniques are successful in reducing the weight of a sole without adversely effecting the performance of the shoe; little, if any, attention has been given to the upper of the shoe as a way of reducing total shoe weight.
On the other hand, efforts to increase the amount of support provided to the foot involve the use of orthotics, plastic inserts or reinforcing members in the uppers of shoes. For example, U.S. Pat. No. 4,813,158 to Brown discloses a mesh reinforcement member which provides added strength and lateral support to the upper of the shoe.
Plastic heel counters, which are now quite common in the shoe art, may be assembled within the shoe upper to provide increased lateral support to the heel and ankle of the wearer. Still another method of providing support to various areas of the foot involves the use of layered leather bands or straps.
More recently, athletic shoe manufacturers have turned to inflation systems situated within the upper as a means of increasing support to the foot. The system, when properly inflated, supportively conforms to the contour of the wearer's foot preventing movement of the foot within the shoe which could cause injury to the wearer's muscles or joints. The inflation system is assembled separately and is incorporated into the shoe between the upper and the interior shoe lining.
With each of the aforedescribed needs in mind, one objective of the present invention is to provide a lightweight upper which is securely fitted to the foot.
A further objective is to provide a lightweight upper which offers superior support to the foot of the wearer.
Still another objective is to provide a lightweight upper which offers customized support to the foot of the wearer.
Another objective is to provide an upper for an athletic shoe which moves with the foot of the wearer during increased activity.
A further objective is to provide an upper for an athletic shoe which keeps the user's foot comfortable and dry.
Still another objective is to provide an upper for an athletic shoe which is easily manufactured by requiring as little stitching as possible.